Springfield Marine Plug In Series Aluminum Post Base 9" Round 9in Round. Features a satin finish with high-strength aluminum construction to withstand harsh marine environments. A 3-3/4" hole in the deck is required below the deck mount for installation. Use with any 2-3/8" Plug-In Series Post (sold separately). Features of Springfield Marine Plug In Series Aluminum Post Base 9" Round 9" round base with an 8" hole pattern Satin Finish High-strength aluminum construction Use with any 2-3/8" Plug-In Post (sold separately) 3-3/4" hole in the deck is required below the deck mount Package Contents: Springfield Marine Plug In Series Aluminum Post Base 9" Round Springfield Marine 1300750-1: Plug In Series Aluminum Post Base 9" Round 9in Round